The present invention relates to a bar work loading apparatus for a head traveling type vertical machine tool in which a main spindle having an axis of rotation extending approximately vertically is rotatably supported by a headstock that is movable in the directions of at least two axes. The bar work loading apparatus inserts a bar work into the main spindle from a side thereof closer to a chuck provided at the lower end of the main spindle. The present invention also relates to a bar work loading method for use in a head traveling type vertical machine tool.
There is a head traveling type vertical machine tool having a headstock that rotatably supports a main spindle having an axis of rotation extending in the vertical direction or tilted at a predetermined angle with respect to the vertical direction. The headstock is moved to machine a work held by a chuck provided at the lower end of the main spindle with a machining tool provided below the chuck. The head traveling type vertical machine tool has such advantages that it does not need a transfer loader for transferring a work to the main spindle, and the work transfer mechanism is simplified. Such a head traveling type vertical machine tool is generally used to machine works whose axial length is substantially equal to or shorter than the diameter thereof. There has heretofore been no bar work loading apparatus usable for a head traveling type vertical machine tool to perform a bar work machining operation in which a bar work whose axial length is longer than the diameter thereof is loaded into the main spindle and successively advanced so as to project from the chuck by a necessary length for each machining process, and machining is carried out with respect to the projecting portion of the bar work.
Japanese Patent Post-Examination Publication Number 5-13761 (1993) is publicly known as an apparatus for loading bar works into a vertical lathe that is not of the head traveling type. In the known apparatus, a bar work is loaded into the main spindle from the rear, that is, from above.
If a bar work loading apparatus such as that disclosed in Japanese Patent Post-Examination Publication Number 5-13761 (1993) is applied to a head traveling type vertical machine tool as it is, the overall height of the system comprising the machine tool and the bar work loading apparatus becomes unfavorably high, and the bar work loading apparatus is likely to interfere with the ceiling of the factory. For this reason, the system including the bar work loading apparatus cannot be installed in a low-ceilinged factory. There is also a problem that the axial length of bar works to be machined is unfavorably limited because of the necessity of avoiding interference between the bar work loading apparatus and the ceiling of the factory. Moreover, the operation of setting bar works in the bar work loading apparatus placed at a high position is not easy, and there is a danger of an accident occurring. That is, the operator may drop a bar work accidentally. Thus, the bar work setting operation also involves a problem in terms of safety.